Pipes.Safe.Prelude

Simple resource management functions

Handle management

withFile :: MonadSafe m => FilePath -> IOMode -> (Handle -> m r) -> m r

Acquire a Handle within MonadSafe

The file is opened in text mode. See also: withBinaryFile

withBinaryFile :: MonadSafe m => FilePath -> IOMode -> (Handle -> m r) -> m r

Like withFile, but open the file in binary mode

See hSetBinaryMode for the differences between binary and text mode.

openFile :: MonadSafe m => FilePath -> IOMode -> m (ReleaseKey, Handle)

Acquire a Handle within MonadSafe

The ReleaseKey can be used to close the handle with release; otherwise the handle will be closed automatically at the conclusion of the MonadSafe block.

The file is opened in text mode. See also: openBinaryFile

openBinaryFile :: MonadSafe m => FilePath -> IOMode -> m (ReleaseKey, Handle)

Like openFile, but open the file in binary mode

See hSetBinaryMode for the differences between binary and text mode.

String I/O

Note that Strings are very inefficient, and I will release future separate packages with ByteString and Text operations. I only provide these to allow users to test simple I/O without requiring any additional library dependencies.

readFile :: MonadSafe m => FilePath -> Producer' String m ()

Read lines from a file, automatically opening and closing the file as necessary

writeFile :: MonadSafe m => FilePath -> Consumer' String m r

Write lines to a file, automatically opening and closing the file as necessary

Registering/releasing

allocate

Arguments

:: MonadSafe m

=> Base m a

Acquire

-> (a -> Base m ())

Release

-> m (ReleaseKey, a)

Acquire some resource with a guarantee that it will eventually be released

The ReleaseKey can be passed to release to release the resource manually. If this has not been done by the end of the MonadSafe block, the resource will be released automatically.

allocate_

Arguments

:: MonadSafe m

=> Base m a

Acquire

-> Base m ()

Release

-> m ReleaseKey

Like allocate, but for when the resource itself is not needed

The acquire action runs immediately. The ReleaseKey can be passed to release to run the release action. If this has not been done by the end of the MonadSafe block, the release action will be run automatically.